Antioxidants



Patented Jan. 11, 1949 2,458,780 AN-TIOXIDANTS Louis. H. Rowland, Watertown,

Rubber Company,

United States} Conn.,, assignor to New York,

N. Y1, a corporation of New Jersey No; Drawing.

Application December 6, 1945, Serial No. 6332267.

1- Claim. (01. 200-800) This invention relates to anewclass. oi anti.- oxidantsor ageeresisters for organic substances which-- tend; to deteriorate by absorption or oxygenfromthe. air, e. g.,.rubber or alliedigums unr saturated fatty" oils. sue-h as unsaturated vegetable.- oi-ls, essential: oils, petroleum oils and. their derivatives,. such as gasolines, soaps, aldehydes, synthetic. resins, turpentine; insecticides, such. as derris root, cube root, and pyrethrum, and. the like.

- According to: the invention, the organicsubstances. are. incorporated. with av com-pound having a heterocyclicring, composed of 3 carbons and 2 nitrogensarranged so. that the 3. carbons are joined together and? the. together, one ofthe nitrogens being joined tohydnogen, said: carbon. of a keto group. The. chemicals. are referred to as ketopyrazolines (pyrazolones)...

The pyrazolones of this. invention contain the nucleus. I

Pyrazolone, itself, namely 5-pyrazolone, has the structure CH.-CH1 \La 41;

2' 5 \l% N n which; is in tautomericequilibrium with 1105011 HO-CH no--on, 4L a! a 4L HNl' 3*:0, N1" a"-'on,-"'and N2- 5 -on N N H n: (ii-pytazolone) (enol) (enol) this invention, the they occur are. tobe mpyrazolone-chem- For the purposes of tautomers and enolsa where consideredequivalents oithe icals.

The preparation of these pyrazolones is well known. As general preparative references, the following are given: Hans Meyer, Synthese Der Kohlenstoff-verbindungen (Heterocyclen) pages 1006-1008 (Julius Spring, Vienna, 1940). Julius Cohen-Organic Chemistry, part 1, page 261 (Longmans, Green and Co., New York, 1919).

Exemplary of preferred compounds falling within the scope or this invention are: pyrazolone, l-phenyl S-pyrazolone, 2-methy1 l-phenyl 5- pyrazolone, 3-methyl S-pyrazolone, la-methyl 5- pyrazolone, 3,4-dimethyl 5-pyrazolone, 1,3,4-trimethyl 5-pyrazolone, l-allyl 3,4-dimethy1 l-phenyl S-pyrazolone, 3 benzyl S-pyrazolone, 3-methyl 4-buty1 5-pyrazolone, l-phenyl 3-methy1 5-py- 2 nitrogens arejoined nitrogen being. directly, connectedto razolone, 3,-methyl 4-lauryl 5.-pyrazolone, 4-cyc1opentyl 3-methy1 1=-pheny1 S-pyrazolone.

The iollowing. examples are given to. illustrate the. preparation and use of the chemicals, the parts being by weight. EXAMPLE 1.-4-N-BUTYL 3-METHYL 5,-PY-

RAZOLONE An aqueous solution (11.7 g.) of hydrazine hydrate is stirred into 37.2 g. ethyl-e-n-butyl acetoacetate. After a short time a crystalline mass is formed. It is heated for an hour on a steam bath during" which time alcohol is evolved and ahigh meltingsolid is formed. Upon recrys tallization from alcohol; 1 2 g. -n-buty1'3'-methy l fipyrazolone, melting- 203-205 C'., are obtained. EXAMPLE 2.-4-N-DODEC.YL 3-METHYL 5- PYRAZOLONE Ethyl e-n-dodecyl'f acetoacetate (13.4 g.)"Kuhn; J. Prakt- Chem. 156'10-3 (1940) and 2.8 g; of an 85% aqueous solution. of: hydrazine hydrate are mixed with stirring. The mixture becomes warm and. soon a white crystalline mass forms. This is heated on a. steam bath for 2 /2 hours during which-time alcohol is: evolved and a high melting solid. is produced. Upon recrystallization from alcohol, 5 g. of 4-n-.-dodecyl 3-methyl 5- pyrazolone, melting at 169-173 0., are obtained.

EXAMPLE 3.-RUBBER TESTS TABLE I Tests on: crude polymer clone; 4-Butyl 3.

razolone 3-Mothy-l l-phonyl B-pyrazolone; 4-Dodecyl fi pyrazolone Stock Chemical Hours Control. 4 3-Methyl 5-pyrazolone. n. 360 3,4-Dimethyl fi-pyrazolone 72 4-Butyl 3-methyl 5-pyrazolone. 72 3-Methyl 1-phenyl5-pyrazo1onc 96 F 4-Dodecyl 3-methyl 5-pyrazo10ne. 48

The rubber stocks are to the following recipe:

compounded according rubber 100 Titanium dioxide 50 Lithopone 1 75' Paraffin oil Zinc oxide Mercaptobenzothiazole 2.0 Tetramethyl thiuram monosulfide v 0.2

242.2 TABLE III N G H I l K L Above Master Batch. 242. 2 3Metl11y fi-pyrazolonei 3-4-Dimethyl 5-pyrazo ne -Butyl S-methyl 5- pyrazolone The stocks are cured 90, minutes at 45 pounds per square inch steam pressure, and exposed to sunlight under glass for several days. Substantially no discoloration occurred during this vex? posure. v

EXAMPLE 4 Mixtures of boiled linseed oiltwith pyrazolones were made up according to the following recipe:

TABn-E IV- l e A B O D E F' Boiled linseed oil 100.0 100.0 100.0 100.0 100.0 100.0 3-Methyl5-py1azo1onc. 1.5 3,4-Dimethyl 5-pyrazolone L5 l-Phenyl-3-methyl 5- Y -1 pyrazolone l. 5 3-Methyl-4-butyl 5- I a pyra-zolone 1.5 3-Methyl-4-lauryl 5- pyrazolone .l 1.5 M

Equal portions of mixtures of A, B, C, D, E, and F are poured into shallow glass dishes and the open dishes exposed to the atmosphere at room temperature. The samples are examined at- 24 hour intervals for appearance of a surface film. The results are recorded in the following table:

Hours of Exposure Before Formation of Film is Ohserved M Sample A (blank) Sample B Sample 0.- Sample D- each of the antioxidants reof the linseed oil.

filling and compounding ingredients may be inproportions may be found useful.

corporated along with the preservative, for example, in the case of a rubber, there may be incorporated accelerators, softeners, etc.

The antioxidant may be incorporated in any type of rubber composition, such as those used for automobile tires and tubes, hose, belting, sheet and thread rubber, rubberized fabrics, molded goods, boots andshoes, etc., whether vulcanized in a mold, in open steam, in hot air, or in the cold by the so-called acid process/ The proportion of the antioxidant may vary from about 0.1% to 5%, although either smaller or greater If the material to which it is added is a liquid such as rubber cement or an oil, the antioxidant may be dissolved therein in a suitable small proportion. The antioxidant may be incorporated into solid substances by milling or mastication, and prepared for incorporation into dispersions or solutions either in powder, paste or solution form, or applied in such forms for incorportion by diffusion, to the surface of vulcanized or unvulcanized rubber goods. 1

Having thus described my invention, what I claim and desire to protect by Letters Patent is:

A rubber composition containing from 0.1 to 5% by Weight of a fi-pyrazolone from the class consisting of 5pyrazolone, l-phenyl 5-pyrazolone, 2-methy1 l-phenyl 5-pyrazolone, 3-methyl 5-pyrazolone, 4-methyl 5-pyrazolone, 3,4-dimethyl 5-pyrazolone, 1,3,4-trimethyl 5-pyrazolone, 4-

allyl 3,4-dimethyl l-phenyl 5-pyrazolone, 3-benzyl fi-pyrazolone, B-methyl 4-butyl 5-pyrazol0ne, l-phenyl B-methyl li-pyrazolone, 3-methyl 4- lauryl 5-pyrazolone, 4-cyclopentyl 3-methyl 1- phenyl S-pyrazolone.

LOUIS H. HOWLAND.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Pedersen Aug. 14, 1945 

